This study was carried out to investigate the effects of reciprocal peer Instructional strategy on Student Academic achievement  and  interest in Business Studies in Kwara State. Three research questions were generated and three null hypotheses were formulated to guide the study. The study was a non-equivalent control group quasi-experimental design, involving one treatment and one control group. A total of 134 Junior secondary class two students from three district junior secondary schools in Patigi; LGA Education Zone made up the sample for the study. In each school, one intact class was randomly selected and the intact classes were also randomly assigned to experimental and control conditions. Three instruments namely: the Business Studies Achievement Test (BSAT) Business Studies interest Inventory (BSII) and the Business Studies Lesson Plan namely: the Reciprocal Peer Tutoring Strategy Lesson Plan and Conventional Lesson Plan, were developed, by the researcher. The reciprocal peer tutoring strategy lesson plan was used for the experimental group while the control group received training using the conventional teaching method. The data obtained were analyzed using mean scores, standard deviation, and 2 x 2 analysis of covariance (ANCOVA). The major findings of the study were that intervention using reciprocal peer strategy significantly improved the achievement and, interest in Business Studies Junior secondary school students; and that gender had no significant influence on the achievement and interest in Business Studies students based on the reciprocal peer tutoring strategy; that gender grouping was not a significant factor in the achievement and interest in Business Studies. A major educational implication of the findings was that training in reciprocal peer tutoring strategy improves achievement and interest, this suggests that teachers would achieve better results if trained on how to use the RPT strategy.